Manufacture of fiber board



May l2, 1931. As. H. HussY nmzmcruns 'or FIBER Bonn med ism-cn 31. 1930 Y haci/@in E 745057Z J J1( A5-6%' @f Puf/W9@ MW, @d

Patented Mey l2, 1931' Him-Issey, or SPRINGFIELD, omo

EANUFACTURE F FIBER. BOARD Application led March 31, 1980. Serial No. etbll.

This invention relates to the formation of relatively thick ber webs or sheets and, among other objects aims to provide apparatus for treating the surface of the sheet and controlling the uniformity of the thickness of the formed web or sheet.

The invention lmay be readily understood by reference to one illustrative construction embodying the invention and shown in the accompanying drawing.

ln said drawing the figure is a transverse section, more or less diagrammatic in character, showing a forming cylinder with associ-v ated accessories and a formed web leaving w the cylinder.

In the manufacture of thick fibrous sheets, `Whether by a continuous process or in forms, it is diicult to obtainuniformity of thickness of the product even with the most approved means of securing uniformity of dis'- tribution of ber.

. .The illustrative apparatus embodies the invention as applied to the formation of a thick brous web on a cylinder machine. Continuous thick brous Webs are -usually formed on cylinder machines from a free Stock which rmits the building up of a thick layer o pulp on vthe cylinder. This layer may and often does exceed an inch 1n thickness. After pressing,- removal of the water and drying, the nal dry sheet While still thick in character, is usually less than half the thickness of the initially formed I layer. While it is possible to control to some extent the thickness of the layer formed on the cylinder by the character of stock used, del gree of suction in the cylinder, and speed of rotation of the cylinder, such methods of con-- trol do not always resultin a sheet which is uniform in thickness throughout. This is particlllarly true when a very wide web is formed,

such, for example, as in the makin of an insulating board wherein the we p may be twelve feet in Width.' On such wide sheets it is particularly diicult to maintain pulp of uniform character throughout the width of the cylinder. While the head box is usually provided with means for providing some variation in the freeness or thickness of the stock to secure uniformity,`nevertheless the result is only approximate.

y According to the present invention I provide a web of uniform thickne by the withdrawal from the web of the ber comprising the excessivel thick portions in the sheet, and thus provide a web of uniform thickness which, when it has been fully pressed and the water removed, results in a sheet of uniform thickness. The method isa departure from orthodox practice under which it was considered objectionable to attempt any such manipulation or treatment of the surface of the formed web.

, `.Any disturbance of the formed web would I not only very likely impair the sheet but any manipulation of the bers would be extremely diicult because of the character of bers themselves which in wet or soft condition are not readily suited for treatment.

The present apparatus embodies a conventional form of cylinder machine com rising a vat 10 carrying the stock in whicli) rotates the forming cylinder 11.` The interior of the cylinder is provided with customary suction boxes vby means of which the degree' and application of suction in various regions may be controlled. These are of usual construction andarrangement and need not be illustrated. A pressing felt 12 running over rolls 13 and 14 is rovided for pressing the sheet in advance mi) the point where it leaves the cylinder. This felt and the ro'lls serve to press the'sheet to approximately half the maximum thickness of the formed web or layer, but after the sheetv leaves the felt it `expands somewhat. Later pressing and dry` ing of the sheet reduces it to its nal (d thickness. The apparatus for evening t brush roll 15 (in this case about ve mches in diameter and having strai ht wire bristles) whose shaft 16 is made a justable to and from the sur'face of the web. It is rotated in minute in a direction against the direction of travel of the web. Its position is adjusted sheet is herein represented by a rotatin wire relative to the web so that it will enga e and remove enough of the pulp on the sur ace to bring it to a uniform thickness. The brush the present case at about 600 revolutions per velop vresistance in (and therefore compress) the sheet. Any compression or disturbance of the sheet would result in an erratic removal of ber which would produce as many irregularities-in the sheet as existed before treatment. l-Ordinaril the irre larities in thickness do not excee by more t an a thirty.-

second or sixteenth of an inch the regions of minimum thickness in the sheet, hence, ordinarily itis not necessa to adjust the roll to remove more than a t irty-second or sixteenth of an inch in thickness in the regions of the greatest thickness ofthe sheet. rIhe speed of rotation of the roll is made great enough so that centrifugal force will cause the pulp to clearor leave the roll. The ty e` of roll may conveniently be similar to t e type of wire brush used in treating cloth.

vThie brush roll also serves advantageousl as a gauge (which indicates whether the stoc is substantially uniform throughout the width of the cylinder) by which the head box may be adjusted to regulate the freeness of the stock throughout the width of the cylinder.

A rotating paddle wheel 17 is advantageously placed adjacent the level of the pulp in the vat and rotating in a direction away from the cylinder in order to kick away the pulp` removed by the wire brush and prevent it from attaching itself to the formed web until after it has been thoroughly mixed' and uniformly distributed in the stock. The removal of the pulp'by the wire brush does not impair it in any way nor render it'incapable of beingi uniformly distributed throughout the stoc j A wire brush roll 18 similar to the brush roll 15 is arranged to engage the face of the web after it leaves the c linder in order to obliterate the marks of t e cylinder usually appearing on the face 19 of the web. The function of roll`18 is not to remove any of the pulp but merely to scarify o r teasel the surface suiciently to obliterate the cylinder marks. This is accomplished merely by pulling up or raising the ber slightly. The roll 18 is made to rotate at about 600 revolutions per minute in the direction of travel of the sheet. The sheet is, of course, supported adjacent the roll by appropriate means not here shown. In order to remove any ber adhering to the roll 18 a cleaning roll 20 similar to roll 18 is provided to engage the latter and remove such ber.

It will be understood that the apparatus above shown illustrates only one form of cylinder apparatus.- The location of the eveningv roll 15 depends obviously upon the character of the forming apparatus. For exam le,

where thick webs are formed on two cylin ers and then broughttogether to form a sin le sheet aggregating in thickness that of t e two webs it is desirable to provide an evening roll -or engaging each face of the sheet since irregularities in thickness may occur on both of the formed webs. For this reason it ordinarily wouldv not suice to treat only one face of the @sheet with an evening device. Where the thick sheets are made in flat forms or molds, the latter may readily be passed under a similar rotating brush roll so that the surfaceof the formed wet sheets may be evened.

Obviously the invention is not limited to the details of the illustrative apparatus since these may be variously modie Moreover, it is not indispensable that all features -of the invention be used conjointly since various features may be advantageously employed in different combinations and sub-combinations.

Having described my invention, I claim:

1. The method of formin thick ber sheets the removed stock foi` re-use.

3. The method of formin thick ber sheets which is characterized by orming the sheet from wet stock and whilev the sheet is still wet applying a rotating brush thereto to remove surface inequalities; and rotating said brush at suicient speed to throw off by centrifugal force, the stock removed from t e sheet.

4. Apparatus of the characterv described Y comprising in combination means for forming a thick ber sheet from wet stock, and a rotating brush engaging the surface of the wet sheet to remove surface inequalities.

5. Apparatus of the character described comprising in combination, cylinder apparatus including a vat and forming cylinder for forming a Continous wet sheet of substantial thickness, a rotating brush associated with a forming cylinder to remove surface inequalities from said sheet,'said brush being arranged to discharge the removed stock into the vat.

6. Apparatus of the character described arranged to discharge the removed' stock into l the -vat and a device for preventing the removed stock from directly adheringto the formed sheeton the cylinder.

7. Apparatus of the character described comprising in combination mechanism including a forming wire for formint a. thick fibrous sheet, a rotatin 'brush ligh y engaging the surface of thes eet oppositethejvire to even such surface, and another rotating brush positioned `to engage the face ofthe sheet next the Wire after it has left the wire to obliterate formingfmarks on such face.

-8. Apparatus of the character described comprising in combination mechanism for formingpa thick fibrous sheet and rotating brushes lightly engaging opposite faces of the sheet after formation to even the surfaces of such sheet. c

In witness of the foregoing I affix my sig' ERWIN HUSSEY.

nature. 

